.meta file comparison

I need to compare the code (diff it) for a single project that has two very different branches...

Suppose I take project A, which is based on Unity 5.X, and I import it into the latest 2017.2.X, then save it all out. And I have project B, which is based on Unity 2017.1.X, and I also import it to the latest 2017.2.X, then save it out.

Now I do a diff (with BeyondCompare) Even having imported into the same Unity format, the .meta files have serialization revision #’s that don’t match, so they’re difficult (impossible) to compare. I’d like to know if there is a way to “thump” the project and have it completely rewrite all the .meta files in the most recent serialization format.